1. Field of the Invention
The present invention relates to devices for delivering a predetermined amount of a substance to a patient, and more particularly to a manual medication delivery device. The present invention also relates to methods of use and kits including such devices.
2. Brief Description of the Related Art
There are many medical conditions that require the administration of liquid medicaments transcutaneously (through the skin) for prolonged periods. Diabetes, for example, may be controlled by daily, or more frequent, injections of insulin. The ability to administer numerous small dosages of insulin has been proven to be the best way to insure tight glucose control for a patient. The National Institutes of Health (NIH) conducted a long-term study of people with diabetes known as the Diabetes Complications and Control Trial (DCCT) were it was determined that the proper management of diabetes requires 4 or more injections of insulin per day. However, current devices either are not convenient or easy to use by patients. Syringes and insulin pens all require the patients to inject themselves and do not provide a convenient or discreet mechanism to accomplish medication delivery.
Since transcutaneous injections are painful and troublesome, and since each injection represents a possibility for infection, injections are spaced at intervals as far apart as possible, resulting in peak and valley concentrations of the medicament in the bloodstream or at the site in the body requiring the medicament, the peak concentrations occurring shortly after the administration of the medicament and the low, or valley, concentrations occurring shortly before the administration of the next injection. This method of administration exposes the patient to the possibility of overdose at peak levels and underdose at valley levels, but was nevertheless the standard method for many years in the absence of a better alternative.
Recently, systems have been developed in which a catheter is semi-permanently implanted in a patient to provide access to a transcutaneous site in a patient""s body, and a liquid medicament is supplied to the catheter from a reservoir. Insigler and Kirtz (Diabetics, 28: 196-203, 1979) describe a portable insulin dosage regulating apparatus which uses an electrically driven mini-pump with an insulin reservoir to periodically dispense a predetermined number of insulin units (U). A small electronic control box is used to set the basal rate of 0.4 U/hr in stages of 0.2 U each. A switch is used to trigger a program that infuses a higher dose for a period of one hour, after which the system automatically goes back to the basal rate.
U.S. Pat. No. 3,963,380, issued Jun. 15, 1976. to Thomas et al., describes a micropump driven by piezoelectric disk benders. Although the pump draws only a small current. it requires a voltage of about 100 volts to drive the pump. Tamborlane et al. (The New England Journal of Medicine, 300: 573-578, No. 11, Mar. 15, 1979) describe a portable subcutaneous insulin delivery system which uses a battery driven syringe pump. The apparatus is bulky and heavy.
A peristaltic motor driven pump has been described by Albisser et al. (Med. Progr. Technol. 5: 187-193 [1978]). The pump weighs 525 g. and consumes 60 milliwatts at maximum pumping rates. This system has a continuous duty cycle. It is bulky and heavy and consumes a relatively large amount of power.
The pump devices that are currently commercially available require the patient to use a very intensive therapy that includes basal rate application of medication and periodic bolus injections. This type of therapy means the patient with diabetes must test their glucose levels to monitor and change the basal rate infusion and the bolus injections. This requires the patient to test frequently by lancing their finger and using expensive test strips to determine their glucose levels.
The inconvenience and difficulty needed to use current devices illustrates the need for a better mechanism to provide medication delivery for patients. This is especially true for those patients that have diabetes who are required to provide regular injections of insulin to treat their disease. In addition, the current problems that have recently been associated with oral medications will make the simplification of injection technology important for these patients who will be placed on insulin therapy to treat their disease since the current oral drugs are being, removed from the market place.
According to a first exemplary embodiment, a portable infusion device comprises a housing having a cavity, a first opening into the cavity, and a second opening into the cavity, the cavity having a curved portion, an elongate flexible member, the flexible member being positioned at least in part in the curved portion, the flexible member being substantially axially incompressible and laterally flexible, and whereby, when a medication ampule including a piston is positioned adjacent to the first opening, the flexible member can be advanced through the curved portion of the cavity to push against and move the ampule piston without substantially compressing the flexible member.
According to a second exemplary embodiment, a portable infusion device comprises a housing having a proximal end, a distal end, a sidewall extending longitudinally between said proximal end and said distal end, an opening formed in at least one of said sidewall, said proximal end, and said distal end, and an interior cavity, an ampule positioned in said housing interior cavity, said ampule including a distal end having a sealed outlet, a piston in said ampule, and said ampule sized and configured to pass through said housing opening, a catheter having a proximal end, a distal end, and at least one lumen extending between said proximal end and said distal end, said catheter proximal end being releasably attached to one of said housing distal end and said ampule distal end, a longitudinally movable plunger positioned in said housing for engaging with and distally moving said ampule piston, manually movable dosage selection means, including interior portions positioned in said housing and selectively engaging said plunger, manually movable exterior portions positioned exterior of said housing for permitting a user of said portable infusion device to select a plunger travel distance, and a manually engageable element connected to said interior portions to move said plunger said plunger travel distance when said interior portions engage said plunger.
According to a third exemplary embodiment, a method of injecting a medication into a patient comprises the steps of providing a portable infusion device comprising a housing having a cavity, a first opening into the cavity, and a second opening into the cavity, the cavity having a curved portion, and an elongate flexible member, the flexible member beings positioned at least in part in the curved portion, the flexible member being substantially axially incompressible and laterally flexible, positioning a medication ampule including a piston adjacent to the first opening, positioning a tube in fluid communication with the medication ampule and subcutaneously in a patient, advancing the flexible member through the curved portion of the cavity pushing against and moving the ampule piston without substantially compressing the flexible member to dispense medication from the ampule, through the tube, and into the patient.
Still other objects, features, and attendant advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description of embodiments constructed in accordance therewith, taken in conjunction with the accompanying drawings.